Right now, the Start a New Marketing Campaign interface only allows you to specify a future start date in one week increments.
Since game days are in sizable increments of real time (25-30 minutes), it can be a real challenge to be sure to be logged into the game and monitoring your time precisely enough to be sure that you time your marketing campaign start time on that seven day cycle, even if planned in advance (important if you want to time the start of one to begin when the current one ends).
This might not be such an issue but for the fact that missing that timing and having a gap, even of only a few days, in a marketing campaign has a negative impact on your CI that you must now "recapture" (i.e. it wastes some of your prior money spent).
If I have a long term campaign and I want to bolster it near its end, I can have an additional campaign started. However, I run into the same problem if I want to have that campaign timed to end with the other campaign (as I want the new one to be equal to the prior two, rather than run two parallel streams of campaigns only because the timing is off). I have to time it for seven day cycle and now month increments.
I'd like to be able to pick a start date, at the very least. I'd also like to be able to pick the end date. If, for whatever game reasons, it requires a minimum of one month commitment per campaign, that is ok.
To me, it would be easiest to use if the campaigns were "sliders" for start and end dates.